This R21 application proposes the development and pilot feasibility trial of One Plus One (OPO), an innovative, theory-driven, two-session, individual-level intervention designed to reduce alcohol use, HIV sexual risk behaviors, and the use of alcohol during sexual activities among older adolescents who experienced housing instability or became homeless after transitioning from foster care to independent living. OPO will integrate brief motivational and cognitive-behavioral strategies to address adolescent alcohol and HIV risk behaviors and incorporate detailed feedback for risk reduction that are tailored to individual risk factors, environmental context, and stage of readiness to change. The intervention requires minimal resources, is readily transferable to other settings, and should be less likely to encounter attrition problems associated with longer, multi-session interventions. Moreover, even if this brief intervention is somewhat less effective than lengthy, more intensive approaches, the increased coverage from ease of dissemination may eventually result in a larger overall public health effect. PUBLIC HEALTH RELEVANCE The proposed research aims to develop and pilot an innovative, theory-driven, two-session, individual-level intervention designed to reduce alcohol use, HIV sexual risk behaviors, and the use of alcohol during sexual activities among older adolescents who became homeless after transitioning from foster care to independent living. This is one of few studies to integrate brief motivational and cognitive-behavioral strategies to address older adolescent alcohol and HIV risk behaviors and incorporate detailed feedback for risk reduction that are tailored to individual risk factors, environmental context, and stage of readiness to change. The intervention requires minimal resources, is readily transferable to other settings, should be less likely to encounter attrition problems associated with longer, multi-session interventions, and may, therefore, eventually result in a larger overall public health effect than more intensive approaches.